The present invention relates to brake rotors for motor vehicles. More particularly the present invention relates to directing airflow into the vents of a vented brake rotor.
Wheeled vehicles are typically slowed and stopped with a braking system that generates frictional forces. One known braking system is the disc braking system which includes a rotor attached to one or more of the vehicle wheels for rotation therewith. The rotor has an annular peripheral section having a pair of outwardly facing annular friction surfaces also known as the braking surfaces.
The disc brake system also includes a caliper assembly secured to a non-rotating component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake pads, each having a backing plate and brake lining material attached thereto. A pad is disposed adjacent each braking surface such that the brake lining material is adjacent the braking surface. The caliper assembly conventionally includes at least one moveable piston operatively connected to the backing plate of at least one of the brake pads. When the driver brakes the vehicle, hydraulic or pneumatic forces move the piston which clamps the brake lining material of the pads against the braking plates of the rotating rotor. As the pads press against the moving rotor braking surfaces, frictional forces are created which oppose the rotation of the wheels and slow the vehicle.
Disc brake systems generate a significant amount of heat during braking by converting the vehicle's kinetic energy primarily to thermal energy when the brake pads are actuated to engage the braking surfaces. As a result, the rotor temperature rises. An excessive temperature rise is undesirable since it may deform the rotor and degrade braking performance.
To improve the performance and wear of disc brake systems, it is desirable to dissipate the heat generated during braking. Vented rotors dissipate heat using a plurality of air passages known as vents which are formed through the peripheral section. For example, some vented rotors include a peripheral section having a pair of annular braking plates connected together in a mutually parallel, spaced apart relationship. Fins connect the inwardly facing surfaces of the braking plates together forming a plurality of passages or vents between the braking plates. As the rotor turns, air flows through the braking plate vents absorbing heat from the rotor thereby cooling the rotor.
The cooling effectiveness of the rotor vents depends in part on the quantity of air moved through the vents. A higher airflow rate through the vents dissipates more heat from the rotor. Therefore, it is desirable to move as much air as possible through the vents as the rotor turns.
It is known that the shape, spacing and orientation of the fins determines the airflow rate through the vents. Various patterns of long and short curved fins have been used to create curved radial vents having varying widths. For example, Shimazu, et al (U.S. Pat. No. 5,427,212) teaches the use of long and short curved fins disposed adjacent each other in alternating fashion to achieve a high airflow rate.
However, it is desirable to provide a vented brake rotor that moves more air through the vents as the rotor turns to improve the cooling effectiveness of the rotor vents during braking.